4 year olds behaviour has led to keeping her locked in the house and no one wants to help

I am all out of ideas. Everyone agrees my daughter behaviour is terrible. We can no longer do anything outside the house even simple things like groceries or just walking around the block.

I'm in no way saying she's terrible she can be a complete angel at times but her behaviour has slowly been getting worse and worse. I am 1000% hell even 1000000000% certain she has ADHD and potentially something else. There is a family history of ADHD on both sides and her dads side of the family has a history of Bipolar and Schizophrenia.

Her daycare will only have her between the hours of 9am and 3pm when they have full staff because and I quote the Center Director 'she is too difficult to deal with'. She has no specific targets just whoever she feels like so I know whatever is going on isn't person based. It also doesn't matter where she is so isn't situation or area based.

She bites, kicks, punches, scratches, digs her nails in, pulls hair, pinches. She's tried ripping piercings out. She screams in people's ears or will just scream at the top of her lungs while we walk down the street. Over Christmas my sister left a pair of scissors unattended and she got her hands on them. When her Dad tried to take them off her (she's tried stabbing both kids and teachers at daycare in the past) she ended up cutting his thumb with them, like I mean full on waited for his hand to close enough and quickly closed the scissors on him requiring 5 stitches in his thumb and she thought it was the funniest thing.

She broken 4 TV's and 2 computers so we've stopped replacing them. She's not allowed near anyone younger then her because she thinks it's hilarious to hit them over the head with heavy objects. She's already broken every single toy she got for Christmas so I tossed them all. All she does is laugh about it.

We've done 1 2 3 Magic, Triple P Parenting, Parenting Kids with ADHD. We've been seeing a Paediatrician every 6 months. We've tried every gentle Parenting technique in the book. We've tried biting back when she bites and she just laughs it off and bites herself. We've tried time in, time out, taking things away, hell we reduced her room to just a frickin mattress from taking shit away and nothing. We've even tried smacking (even though we feel terrible). Nothing works. I've begged the Paediatrician but she said she can't do anything but she starts school which she won't be unless she's home-schooling because none of the 3 primary schools will take her enrolment forms.

What do I do at this point???